package main

import (
	"bytes"
	"fmt"
	"regexp"
)

/**
正则表达式
*/

func main() {
	//This tests whether a pattern matches a string.

	match, _ := regexp.MatchString("p([a-z]+)ch", "peach")
	fmt.Println(match)
	//Above we used a string pattern directly, but for other regexp tasks you’ll need to Compile an optimized Regexp struct.

	r, _ := regexp.Compile("p([a-z]+)ch")
	//Many methods are available on these structs. Here’s a match test like we saw earlier.

	fmt.Println(r.MatchString("peach"))
	//This finds the match for the regexp.

	fmt.Println(r.FindString("peach punch"))
	//This also finds the first match but returns the start and end indexes for the match instead of the matching text.

	fmt.Println(r.FindStringIndex("peach punch"))
	//The Submatch variants include information about both the whole-pattern matches and the submatches
	// within those matches. For example this will return information for both p([a-z]+)ch and ([a-z]+).

	fmt.Println(r.FindStringSubmatch("peach punch"))
	//Similarly this will return information about the indexes of matches and submatches.

	fmt.Println(r.FindStringSubmatchIndex("peach punch"))
	//The All variants of these functions apply to all matches in the input, not just the first.
	// For example to find all matches for a regexp.

	fmt.Println(r.FindAllString("peach punch pinch", -1))
	//These All variants are available for the other functions we saw above as well.

	fmt.Println(r.FindAllStringSubmatchIndex(
		"peach punch pinch", -1))
	//Providing a non-negative integer as the second argument to these functions will limit the number of matches.

	fmt.Println(r.FindAllString("peach punch pinch", 2))
	//Our examples above had string arguments and used names like MatchString. We can also provide []byte arguments
	// and drop String from the function name.

	fmt.Println(r.Match([]byte("peach")))
	//When creating constants with regular expressions you can use the MustCompile variation of Compile.
	// A plain Compile won’t work for constants because it has 2 return values.

	r = regexp.MustCompile("p([a-z]+)ch")
	fmt.Println(r)
	//The regexp package can also be used to replace subsets of strings with other values.

	fmt.Println(r.ReplaceAllString("a peach", "<fruit>"))
	//The Func variant allows you to transform matched text with a given function.

	in := []byte("a peach")
	out := r.ReplaceAllFunc(in, bytes.ToUpper)
	fmt.Println(string(out))
}
